He will next face fellow Spaniard Juan Carlos Ferrero, who had the upper hand against France's Jo-Wilfried Tsonga, prevailing 6-1, 3-6, 7-5 in an entertaining third-round contest on center court.
"Juan Carlos is a player who has won more matches this year on clay and he is coming with big confidence. It is going to be really difficult," Nadal said.
The muscular Spaniard dropped only one game in his second-round match against Dutch qualifier Thiemo De Bakker and it long looked like world number 51 Berrer would taste an even heavier defeat.
"I played better than yesterday because I played higher, I played close to the lines, and my feeling is that I had more control on the ball than yesterday," said Nadal. "Good backhands. Very good forehands down the line." Berrer, a finalist in the Zagreb tournament earlier this year, won only five points in the opening set as Grace Kelly look-likes gathered in the stands on Ladies' day at the tournament.
By the fourth game of the second set, Berrer had doubled his tally, eventually bagging 18 points and triggering wild cheers when he clinched his only game.
A forehand winner down the line ended Berrer's ordeal in a match lasting just 54 minutes and Spanish players enjoyed a fine day on their favorite surface.
David Ferrer ruthlessly brought Ivan Ljubicic down to earth with a 6-0, 7-6 victory and his compatriots Albert Montanes and Fernando Verdasco also reached the quarterfinals.
Ljubicic, who won the Indian Wells Masters last month, could not handle Ferrer's devastating forehand in a one-sided opening set before improving in the second as the Spaniard started to misfire.
Ferrer will face Philipp Kohlschreiber, who advanced after beating fellow German Philipp Petzschner 6-3 6-4, with a possible match up against claycourt machine Nadal looming.
In front of a sparse audience and a few Para gliders swirling around the skies with screeching seagulls, the 11th-seeded Ferrer was initially barely bothered by his opponent's usually lethal first serve.
The eighth-seeded Ljubicic must have been giddy from all the chasing around he had to do as his opponent sent him charging round the court but he recovered in the second set.
He dropped serve in the third game but Ferrer allowed the Croatian to level at 5-5 with a forehand winner.
Ferrer, however, got his act together in the tiebreak, which he clinched 7-4 after Ljubicic netted a crosscourt forehand.
Montanes beat Croatian fourth seed Marin Cilic 6-4, 6-4 while Verdasco, seeded sixth, recovered from a shaky start to see off Czech Tomas Berdych 5-7, 6-3, 6-2.
Argentine David Nalbandian wasted no time in a 6-3, 6-4 defeat of Spaniard Tommy Robredo, setting up a quarterfinal clash with either world number two Novak Djokovic of Serbia or Swiss Stanislas Wawrinka.
